Electric Field Assisted DNA Surface Reactions on the Sub-ms Timescale
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Electric Field Assisted DNA Surface Reactions on the Sub-ms Timescale Ricardo Cabeca1,2, D. M.F. Prazeres2,3, V. Chu1, and J. P. Conde1,3 1 INESC-MN, Rua Alves Redol, 9, Lisbon, 1000-029, Portugal 2 IBB, IST, Av. Rovisco Pais, Lisbon, 1049-001, Portugal 3 Departament of Chemical and Biological Engineering, IST, Av. Rovisco Pais, Lisbon, 1049001, Portugal Symposium BB: Signal Transduction across the biology-technology interface
Electric field assisted DNA surface reactions on the ms timescale R. Cabeça1,2, D.M.F. Prazeres2,3, V. Chu1, J.P. Conde1,3 1 INESC Microsistemas e Nanotecnologias (INESC-MN), Lisbon, PORTUGAL 2 Centre for Biological and Chemical Engineering, Instituto Superior Técnico, Lisbon, PORTUGAL 3 Department of Chemical and Biological Engineering, Instituto Superior Técnico, Lisbon, PORTUGAL
ABSTRACT The on-chip application of single, sub-ms voltage pulses promotes the immobilization of single stranded DNA (ssDNA) probes from a solution to a chemically functionalized SiO2 surface and as well as the hybridization between ssDNA targets from a solution to covalently immobilized ssDNA probes (E-assisted DNA reactions). Compared to diffusion-based surface reactions (in the absence of the applied electric field), an improvement of several orders of magnitude in the kinetics of the immobilization and hybridization reactions is observed with low amplitude (below 2 V) and short duration (100 ns to 1 ms) voltage pulses. E-assisted DNA reactions are demonstrated using mm-size macroelectrodes and then optimized using μm-size microelectrodes.
INTRODUCTION As biosensors based on DNA microarray technology and lab-on-a-chip devices emerge for a wide range of applications, such as gene expression monitoring, disease diagnostics, and pharmaceutical development, a fine spatial and temporal control of the location of the biomolecules and of their biological activity on a solid surface becomes of great technological importance. The use of externally applied dc and ac electric fields, on which the electrophoretic and dielectrophoretic manipulation of DNA molecules is based, has been extensively reported. When
exposed to an electric field, the highly charged DNA strand and the ionic cloud surrounding the molecule exhibit complex dielectric relaxation mechanisms, which depend on the strand length, the ionic properties of the DNA electrolyte solution, and the frequency and magnitude of the applied electric field. Effects such as the orientation of DNA [1], DNA strand stretching [2], spatial positioning [3], and field-induced hybridization and denaturation [4] have been reported. In this work, the electric-field-induced solid-phase immobilization and hybridization of ssDNA molecules on the sub-ms time range is shown to have yields comparable to those obtained for the equivalent passive reactions (without electric field), which take several hours to reach completion. The shape (square vs. sinusoidal) and duration of the applied single voltage pulse influence on the E-assisted DNA reactions is reported. The temp
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